Phase separation in blends of two homopolymers and a diblock copolymer during film casting

Demixing during film casting of blends of polystyrene, polymethylmethacrylate, and a symmetric diblock copolymer of styrene and methylmethacrylate is discussed. The concentration fluctuations in the homogeneous solutions were calculated in mean field approximation. The structures in the homogeneous and demixed solutions and in the dry films were measured by small-angle x-ray scattering, and the morphologies of the dry films were characterized by transmission electron microscopy. The structure of the dry blends is evidently already pre-formed in solution.     

Finite Element Solution of Conical Diffraction Problems

This paper is devoted to the numerical study of diffraction by periodic structures of plane waves under oblique incidence. For this situation Maxwell's equations can be reduced to a system of two Helmholtz equations in R ² coupled via quasiperiodic transmission conditions on the piecewise smooth interfaces between different materials. The numerical analysis is based on a strongly elliptic variational formulation of the differential problem in a bounded periodic cell involving nonlocal boundary operators. We obtain existence and uniqueness results for discrete solutions and provide the corresponding error analysis.     

Compactness in fuzzy convergence spaces

Lowen and Lowen [Applications of category theory to fuzzy subsets (Kluwer, 1992) p. 153] and Lowen et al. [Fuzzy Sets and Systems 40 (1991) 347] recently introduced the category FCS of fuzzy convergence spaces, a topological quasitopos which is a supercategory of FTS, the category of fuzzy topological spaces. In this paper, compactness in FCS is examined. Doing so we found that to define compactness as an absolute property we had to generalize the definition of fuzzy convergence space to fuzzy subsets. All basic theorems are proved including the Tychonoff product theorem. Based on the theory developed here, in a following publication, a Richardson compactification for fuzzy convergence spaces will be given.     

Probing for electrical inclusions with complex spherical waves

Let a physical body Ω in ?² or ?³ be given. Assume that the electric conductivity distribution inside Ω consists of conductive inclusions in a known smooth background. Further, assume that a subset Γ ? ?Ω is available for boundary measurements. It is proved using hyperbolic geometry that certain information about the location of the inclusions can be exactly recovered from static electric measurements on Γ. More precisely: given a ball B with center outside the convex hull of Ω and satisfying (B? ∩ ?Ω) ? Γ, boundary measurements on Γ with explicitly given Dirichlet data are enough to determine whether B intersects the inclusion. An approximate detection algorithm is introduced based on the theory. Numerical experiments in dimension two with simulated noisy data suggest that the algorithm finds the inclusion‐free domain near Γ and is robust against measurement noise. © 2007 Wiley Periodicals, Inc.     

AUTOMATED MECHANICAL STIMULATION AND MEASUREMENT OF BIOLUMINESCENCE IN MARINE DINOFLAGELLATES

A new integrated system for reproducible, automated mechanical stimulation and measurement of bioluminescence (BL) in multiple samples of marine dinoflagellate cell suspensions is described. The system was designed to allow the application of standardized experimental routines to parallel test vials for the purpose of toxicity testing. A sample tray delivered test vials to the position of mechanical stimulation and BL measurement. Mechanical stimulation of BL was applied as sharp rotation-onset of the test vial about its vertical axis. Thus, any direct chemical or physical perturbation of the cell suspension was avoided. A silicon photovoltaic cell measured the emitted light. Stimulation, measurement and recording of BL were integrated and controlled by specially developed software, which runs on a personal computer in the graphic environment of MS-Windows. Precise scheduling, flexible programming and identical repetition of experimental routines are possible in practice. For Gonyaulax polyedra, details of BL, as stimulated and measured with the new system, are presented and discussed. We conclude that the system exhibits specific features that offer wide potential of application in several fields of research on dinoflagellate BL, particularly for toxicity testing.     

An improved algorithm for satellite-derived UV radiations

The improved algorithm surface irradiance derived from a range of satellite-based sensors (SIDES) is presented in this article. It calculates various types of surface UV intensities, such as biologically weighted or unweighted UV spectra, integrated doses or irradiance at specific wavelengths, using data from satellite instruments. These surface UV data are mainly useful for environmental impact or process studies where high accuracy or a high temporal resolution is required. In contrast to several previous studies, SIDES has been validated with spectral measurements. By this method an averaging of positive or negative deviations over the complete wavelength range is avoided. This is especially important for UV wavelengths around 300 nm where biological effectiveness is highest. The results of SIDES deviate less than 7% from ground-based observations for wavelengths between 295 and 400 nm. In contrast, the corresponding deviations of the joint research center algorithm escalate for shorter wavelengths, reaching 35% at 295 nm. This large deviation is due to an inaccurate interpolation procedure that has been detected by spectral analysis. Thus, spectral validation is demonstrated to be an appropriate tool to detect weaknesses in such an algorithm and provides information essential for improvement.     

The Fermi doublet V2−V3 + V4 of CH3CN as a probe of molecular interactions

The Fermi doublet V₂?V₃ + V₄ of CH₃CN in basic, inert and acidic solvents has been studied by IR and Raman spectroscopy. The values of W, the Fermi coupling coefficient, obtained from IR spectra varies with the nature of the solvent while W evaluated from Raman data remains constant at 12.5 ± 0.5 cm^?1. The similar effects of Bronsted and Lewis acids on the band frequencies and intensities is evidence that the CN group complexes with acids via the N atom “n” electron pair and not the π bond.     

Beiträge zur Chemie des Phosphors. 111. 1,2-Dichlor-1,2-di-tert-butyldiphosphan

Contributions to the Chemistry of Phosphorus. 111. 1,2-Dichloro-1,2-di-tert-butyl-diphosphane The reaction of tri-tert-butyl-cyclotriphosphane, (t-BuP)₃, with phosphorus(V) chloride (molar ratio 1:2) leads to the title compound Cl(t-Bu)P? P(t-Bu)Cl ( 1 ), which is remarkably stable against disproportionation reactions. As the first 1,2-dichloro-1,2-diorganyldiphosphane, 1 has been isolated in a pure state and was thoroughly characterized. At room temperature, 1 exists in a mixture of the d,l and meso form (about 20:80). The mutual repulsion of the negative polarized Cl atoms and their preferred gauche arrangement to the free electron pairs of neighboured P atoms leads to a gauche-conformation of the lone electron pairs in the d,l- and to a trans-conformation in the meso-configuration.